31210-ZW9-801 Honda MOTOR UNIT, STARTER (Honda Code 6640593).

Laptop Does Not Connect
If the laptop does not connect to the DCU, ensure the following:
Check if a VPN on the laptop is active. The laptop will not connect to the DCU if a VPN is active. Deactivate the VPN on the laptop and check the connection.
Check the DHCP server on the DCU. The DHCP server must be turned on to establish a connection with the laptop. Use the following steps to enable the server.
Press and hold "Home" to bring up the menu.
Press the "Settings" option and then select "Connect to PC".
Press "Enable". The box next to the option should now be checked. Select "OK".
Unplug the Ethernet cable from the laptop and plug the cable back into the appropriate slot. The laptop should connect to the DCU.New Sensor Not Appearing on the DCU
In the DCU "Troubleshooting" screens, verify that the newly installed sensor is appearing in the appropriate list and showing a value. The sensor should appear under the "Voltage Sensor" troubleshooting menu.If the sensor is not displayed in the list, refer to the Programming Guide, LEBM0063, "Cat A&P Controls Programming Guide".SPN Displayed With No Description
If the alarm list displays an SPN number without a description, ensure the following:
Check that the DCU firmware is up-to-date. If the DCU has outdated firmware, download the latest firmware on SIS web (sisweb.cat.com).
Check if the device has an unrecognized SPN. If a device has been added to the engine/genset with an unrecognized SPN, the customer can submit a request through the Dealer Solutions Network(DSN) to add a new SPN to the DCU firmware.New DCU Configuration File Does Not Appear
If a new DCU configuration file has been loaded and does not appear after rebooting, update the firmware on the DCU. The configuration file was built on firmware that is newer than what is on the DCU.DCU Displays Different Screens or Missing Information
If the DCU displays different screens or is missing information, check the configuration file on the DCU. If the customer has a genset, the configuration file could be a prop file. The same applies to a prop engine. If a genset configuration file has been uploaded to the DCU instead of a prop file, the display will have incorrect or missing information. Use the following steps to find the configuration file on the DCU.
Illustration 1 g06034909
Finding the configuration file
From the "Menu" screen, select the "Help" option.
Select "Version Information". The configuration file will be the bottom line. Refer to Illustration 1.New J1939 Device Does Not Appear on the DCU
Check the DCU programming if a new J1939 device has been added but is not appearing on the DCU. The DCU must be programmed for each J1939 device. Refer to the Programming Guide, LEBM0063, "Cat A&P Controls Programming Guide" for information on programming the DCU.DCU Widgets Display Blank Information
If only some widgets are displaying "- - - -", ensure the following are broadcasting J1939 information
The Engine ECM
The RTD module
CDVR
If most widgets are displaying "- - - -" and the alarm shows "J1939 Bus Disabled", do the following:
Acknowledge the alarm to reset the DCU. Recheck the widgets.
If widgets are still displaying "- - - -", check for damaged or unplugged wiring. Check the resistor at X4 (Schematic - 17R16), and DCU connector #1.Note: The MECPII can have Engine ECM and Powertrain controls. The MGCPII can have controls such as the Engine ECM , PAM, CDVR, and RTD.Jacket Water Heater Control Does Not Work
If the engine speed is greater than "Low Idle", the jacket water heater should be off.
Ensure that the HTC Expansion Water Tank Level is closing. With a multimeter, ensure that there is 24V from the panel on connector C-2 (pin 15). When the switch is closed and water level is "OK", ensure that there is 24V from the switch return on connector C-2 (pin 16). The relays at schematic locations 5K28 and 8K9 should be closed (short circuit) to enable the jacket water heater. Check for any damaged or disconnected wiring. Refer to page 11 of the schematic for heater control wiring.DCU Error Message: "No Connection to SDU 404"
This error message indicates a loss of connection to the SDU. Check for damaged or unplugged wiring to and from the SDU (refer to page 17 of the Schematic). The SDU has an internal circuit breaker that might have tripped. The breaker resets after a short period.Ensure the circuit breaker (Schematic - 4Q25) is functioning properly. Check for damaged or unplugged wiring.The DCU Modbus Register Does Not Activate
If the DCU Modbus Register does not activate for a J1939 DM1 alarm, check the following:
There are two Modbus Registers for alarms
19xx registers only show DCU configured alarms.
50xx registers show DM1 alarms. These registers must be used to trigger DM1 alarms.
If the modbus is incorrect, check the CAT Installation Drawing for modbus assignments.DCU Shows No Information on the Generator Screen
Ensure the following if the DCU does not show information on the generator screen:
The PAM is only powered by the generator. No information will be available if the genset is not running or generating voltage. Ensure that the genset is running.
Ensure that the PAM is connected to the panel if there is still no information being displayed.The DCU Display Does Not Sleep
Ensure the following if the DCU display does not go to sleep in "Off" mode.
Check for active alarms. The DCU will not go into sleep mode if active alarms have not been acknowledged.
Check the DCU configuration. The configuration might not be set for sleep mode. Refer to the Programming Guide, LEBM0063, "Cat A&P Controls Programming Guide".
Check for damaged or disconnected wiring between the ECS switch and terminal 4 on the DCU (Schematic - 4S9).DCU Primary and Secondary Power Supply Alarm Diagnostics Active
The DCU will generate these alarms if power is lost on one supply and the other keeps the system running. When the DCU loses primary power, two alarms will appear. These alarms are "Primary Power Failure" and "Power Source Change". Secondary power failure results in the alarm "Secondary Power Failure".
Illustration 2 g06044354
Ensure that the panel isolation breakers are not tripped (Schematic